In general, in a compressor constituting a refrigerant circuit for performing a refrigeration cycle, lubricating oil (refrigerator oil) is used in order to enhance the lubricating performance of a sliding part of a compression mechanism in the interior of the compressor. For this reason, the lubricating oil is included in refrigerant discharged from the compressor. However, when the refrigerant containing the lubricating oil flows into a refrigerant circuit on the exterior of the compressor, a problem emerges in that there is a deficit of lubricating oil in the interior of the compressor and poor lubrication of the sliding part, and in that the lubricating oil sticks to a heat transfer tube in the interior of a condenser and a heat transfer action is inhibited, and others. In view whereof, there has been proposed in the past a configuration for separating out the lubricating oil from the refrigerant compressed in the compressor and for returning the lubricating oil to the compressor, in order to prevent the refrigerant containing the lubricating oil from circulating through the refrigerant circuit.
For example, Patent Literature 1 (Japanese Unexamined Publication No. 5-223074) recites a scroll-type compressor which is connected to an oil separator for separating out lubricating oil from refrigerant discharged from the compressor. A discharge tube installed on an upper surface of a casing of this scroll compressor is in direct communication with the oil separator, which is installed on the exterior of the compressor. Refrigerant discharged from the discharge tube is sent to the interior of the oil separator and passes through oil separating means in which a fine metal wire is formed in a roll, the lubricating oil being thus separated. The lubricating oil separated out from the refrigerant is stored in an oil reservoir chamber in the interior of the oil separator. This oil reservoir chamber communicates with a space at an upper part of the oil reservoir chamber in the interior of the compressor, via an oil return flow path, which has resistance. As such, the lubricating oil stored in the oil reservoir chamber in the interior of the oil separator is returned to the oil reservoir chamber in the interior of the compressor, via the oil return flow path.